I love fixed blades and usually have one with me, but I've found (somewhat to my consternation) that no fixed blade is as easy or quick to use and put away as a one-handed folder. For all those little jobs like opening a box or cleaning up a piece of cut PVC pipe or nipping off a sickly tomato branch or removing an old registration sticker, the one-handed folder is hard to beat. Being able to draw, cut, and replace the knife with one hand is not the domaine of the pocket fixed blade.
I think fixed blades really excell if you have more than one or two cuts to make, but unless you're carying in a fairly large belt sheath, reholstering takes two hands.
So I carry both, but if I'm only carying one it's the folder. I tried giving the folder up for a small fixed blade but found I was going backwards.